Nu Eridani

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ν Eridani
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 04h 45m 30.15038s[1]
Declination −03° 15′ 16.7765″[1]
Apparent magnitude (V) +3.930±0.023[2]
Spectral type B1.5 IV[3]
U−B color index −0.879±0.007[2]
B−V color index −0.210±0.009[2]
Radial velocity (Rv) 14.9[4] km/s
Proper motion (μ) RA: +0.25[1] mas/yr
Dec.: −1.97[1] mas/yr
Parallax (π) 6.25 ± 0.19[1] mas
Distance 520 ± 20 ly
(160 ± 5 pc)
Absolute magnitude (MV) −2.84±0.15[3]
Mass 9.3±0.3 M
Radius 6.2±0.5 R
Luminosity 7,943 L
Surface gravity (log g) 3.85±0.05 cgs
Temperature 22,000±250 K
Rotational velocity (v sin i) 26±2 km/s
Other designations
ν Eri, BD−03° 834, 48 Eridani, FK5 169, HD 29248, HIP 21444, HR 1463, SAO 131346.[5]

Nu Eridani (ν Eri) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.93.[2] The distance to this star is roughly 520 light years, based upon an annual parallax shift of 0.00625 arcseconds.[1] If the star were 33 ly (10 pc) from the Sun, it would be the brightest star in the night sky with an apparent magnitude of −2.84.[3] (Currently, the brightest star is Sirius at magnitude −1.46.)

This is a B-type subgiant star with a stellar classification of B1.5 IV.[3] It is a hybrid pulsator variable, lying as it does on the overlapping instability strips for Beta Cephei variables and slowly pulsating B-type stars.[6] The star shows at least fourteen pulsations frequencies, with nine that also display radial velocity variations.[7] It has about nine times the mass of the Sun and six times the Sun's radius. Nu Eridani shines with 7,943 times the solar luminosity from its outer atmosphere at an effective temperature of 22,000 K.[3]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Nieva, M.-F. (February 2013), "Temperature, gravity, and bolometric correction scales for non-supergiant OB stars", Astronomy & Astrophysics, 550: A26, arXiv:1212.0928Freely accessible, Bibcode:2013A&A...550A..26N, doi:10.1051/0004-6361/201219677. 
  3. ^ a b c d e f Nieva, María-Fernanda; Przybilla, Norbert (2014), "Fundamental properties of nearby single early B-type stars", Astronomy & Astrophysics, 566: A7, arXiv:1412.1418Freely accessible, Bibcode:2014A&A...566A...7N, doi:10.1051/0004-6361/201423373. 
  4. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W. 
  5. ^ "nu. Eri -- Variable Star of beta Cep type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-11-03. 
  6. ^ Moravveji, Ehsan (January 2016), "The impact of enhanced iron opacity on massive star pulsations: updated instability strips", Monthly Notices of the Royal Astronomical Society: Letters, 455 (1): L67–L71, arXiv:1509.08652Freely accessible, Bibcode:2016MNRAS.455L..67M, doi:10.1093/mnrasl/slv142. 
  7. ^ Daszyńska-Daszkiewicz, J.; Walczak, P. (March 2010), "Complex asteroseismology of the β Cep/slowly pulsating B-type pulsator ν Eridani: constraints on opacities", Monthly Notices of the Royal Astronomical Society, 403 (1): 496–504, arXiv:0912.0622Freely accessible, Bibcode:2010MNRAS.403..496D, doi:10.1111/j.1365-2966.2009.16141.x.